Modeled Detection and Recognition Range for a Polarization Filtered FLIR Sensor

A model has been developed to evaluate the influence of polarization filtering on the detection and identification range of a thermal sensor. The scenarios evaluated were based on environmental parameters and ship temperatures recorded during the EOPACE measurement series in San Diego bay in 1996. These scenarios represent a FLIR sensor on a platform in level flight at 100 m or 1000 m approaching a ship target, represented as a gray body at the recorded ship hot-spot temperature. The polarized version of the SEARAD sea radiance code was used to provide sea background radiance and propagation characteristics for both ship target and background. Apparent Temperature Difference was calculated versus range for horizontally polarized and unpolarized imaging. Maximum range was determined for both cases by comparison to a generic Minimum Resolvable Temperature function representing a typical LWIR Common Module FLIR. Preliminary results for the polarized case predict greater apparent temperature difference at ranges to around 10 kilometers. Unresolved apparent anomalies in the computed results suggest that target temperatures are under-estimated. Empirical correction of the zero ranges temperature difference suggests polarized identification range of the order of 25 to 30 km. Improvements to the modeling are proposed.